Burglar alarm



March 19, 1935. F. H. STOTTS 1,995,032

0 BURGLAR ALARM Filed Jan. 8, 1934 2 Sheets-Sheet 1 March 19, 1935. F.H. sToTTs Y 1,995,032

BURGLAR ALARM Filed Jan. 8, 1934 2 Sheets- Sheet 2 3 WW K15: 452 0555.

Patented Mar. 19, 1935 UNITED STATES PATENT OFFICE BURGLAR ALARM Francis11. Stotts, Wynne, Ark.

Application January 8, 1934, Serial No. 105,801

2 Claims. (Cl. 200-52) This invention relates to burglar alarms forinstallation in dwelling houses, banks, oflices, factories, and otherbuildings and has for its object to provide a comparatively simple andthoroughly '5 eflicient device of this character which willautomatically sound an alarm should an attempt be made to burglarize thebuilding by forcing an entry through a door, window, or other closurethereof. 10 A further object of the invention is to provide a burglaralarm including a. plurality of guard or detector wires positioned atsuitable intervals across a door or window and operatively connectedwith an electrical switch so that should a burglar cut the panel of adoor or the glass of a window in an effort to obtain access to the lockthereof, the guard or detector wires will be severed or otherwiseactuated to operate the switch and sound an alarm.

A further object is to decrease the cost of installation by mounting theswitch units on a carrying bar orv support so constructed that anydesired length thereof may be cut off to fit the width of the door orwindow to be protected and said bar, with the required number of switchunits properly mounted thereon, quickly secured in position, thuseliminating the expense of in,- dividual installation and wiring of theseveral switch units.

A further object is to provide a burglar alarm which will operate eitheron a closed or open circuit and which will continue to ring until theswitch is cut off.

A still further object of the invention is generally to improve thisclass of devices so as to increase their utility, durability andefficiency.

In the accompanying drawings forming a part of this specification and inwhich like numerals of reference indicate corresponding parts in all thefigures of the drawings,

Figure 1 is a perspective view of the interior of a building equippedwith a burglar alarm constructed in accordance with the presentinvention. 1

Figure 2 is a perspective view, partly broken away, of one of theswitch-carrying bars'and its associated parts,

Figure 3 is a vertical sectional view taken on the line 3-3 of Figure 2.

Figure 4 is a diagrammatic view of the electrical circuit.

The improved burglar alarm, forming the subject-matter of the presentinvention, is designed for installation in dwelling houses, oflices,factories, and other buildings, and by way of illusextended downwardlywithin the tration is shown in connection with a dwelling house in which5 designates one of the inner walls, 6 a door and 7 a window ofconventional-construction. I p

In carrying out the invention, I employ a car- 5 rying bar or support 8formed of insulating mate- 'cisions 11 formed therein and the metalbetween the incisions pressed outwardly to form sockets 12 adapted toreceive the adjacent ends of switch arms 13. The inner end of eachswitch arm is adjacent socket l2 and thence bent upwardly to form a hook14 which serves to rigidly anchor the switch arm to the socket.

Each switch arm is preferably formed of spring metal, the outer endthereof being depressed to form a hook 15 to which is secured, in anysuitable manner, the adjacent endof a guard or detector wire 16, thelower end 'of which is fastened by a nail or similar fastening device 17to the bottom of the door 6 or to the window frame so as to anchor thedetector wires in proper pmition across the inner faces of the closures.Secured to the upper edge of each carrying bar 8 is a metal strip 18 andfastened to said strip and to the lower edge of the bar 8'are metalcontacts preferably in the form of loops 19, the intermediate portionsof which are spaced from the conductor strip 10, as best shown inFigure3 of the drawings. Secured to the ends of the strips 10 and 18 are Wires20 which are connected in an electric circuit 21 including a relay 0 22,battery 23, and signal bell or alarm 24 so that, when the arm 13 of anyselected switch engages either the upper or lower end of the'adjacentloop 19, the circuit will be closed through the battery and relay andcause the bell 24 to ring thereby sounding an alarm which will continueto ring until the occupant of the house or building manually opens theswitch 25. The construction of the relay is such that when any switcharm 13 is closed, the coil of the relay will be energized and throughthe medium of its armature close the circuit through the bell and saidbell'will continue to ring until manually shut off, as previouslystated.

Mounted on the door 6 and door jamb, respectively, are contacts 26connected in an auxiliary circuit 27 with the main circuit 21 so thatshould the door be moved to open position the contacts 26 willinterengage and sound an alarm. In connection with the windows of thebuilding, I preferably provide each sash thereof with an auxiliary guardor detector wire 28, the upper end of which is connected with one of theswitch arms 13, while the lower end thereof is connected with the sash,as indicated at 29, so that should an attempt be made either to raisethe lower sash of the window or lower the upper sash, a longitudinalpull will be exerted on the adjacent auxiliary detector wire and operatethey switch arm to close the circuit and sound an alarm. Thecarryingbars 8 for the windows are secured to the upper portion of thewindow frame by screws or similar fastening devices while the carryingbars for the doors are secured to the upper portion of the doors and aremovable therewith, as will be readily understood. Each door is alsopreferably provided with an auxiliary detector wire 30 which may beconnected with the door knob so that should the door knob be turned, apull will be exerted on the detector wire to close the switch arm at theupper end thereof and sound an alarm.

As many controlling switches and detector Wires may be positioned acrossthe inner face of a door or window as is found most desirable in actualpractice, but it is preferred to have said wires arranged close enoughtogether so that should a burglar attempt to cut the panel of the dooror the glass of the window in an effort to release the lock, the wireswill either be severed or distorted out of their normal position and ineither event the controlling switches will be actuated to close thecircuit and sound an alarm.

It isproposed to make the carrying bars or strips-8 in relatively longlengths and to install the controlling switches and their associatedparts thereon prior to positioning the bars over the doors and windowsof a building thereby saving time in installing the alarm andconsequently saving the cost of mounting and wiring each individualswitch. In other words, inasmuch as the controlling switches are alreadymounted on the carrying bar, it is merely necessary for the workman tocut or sever a sufiicient length of the bar to agree with the width ofthe door or window to be protected and then fasten the carrying barabove the door or window with screws or similar fastening devices, aspreviously stated, and as these bars, with the switches thereon, can bekept in stock, it necessarily follows that the installation of thesystem in a house maybe materially expedited and a material saving intime and labor V In operation, assuming the detector wires or guards tobe positioned at the rear of the doors and windows of a building, asshown in Figure 1, should a burglar attempt to efiect an entry througheither a door or window of the building, as for instance by cutting thepanel of the door around the lock, or cutting the glass of the window,the adjacent detector wires will either be severed or pressed outwardlyto an abnormal position; Should a detector wire be severed theresiliency of the switch arm 13, connectedtherewith, will cause said armto move upwardly and engage the upper end of the contact loop 19 andclose the circuit through the bell to sound an alarm and should thedetector wire be pressed outwardly or moved to an abnormal position, the

downward pull on the detector wire will cause the arm 13 to engage thelower end of the loop 19 and likewise close the circuit through thebell, it, of course, being understood that under normal conditions thecontact arms 13 are in neutral position. Should an attempt be made toraise or lower the sashes of the window or to open the door by turningthe knob thereof, the auxiliary detector wires 28 and 30 will have adownward pull exerted thereon thus causing the contact arms to engagethe lower portion of the switch loops and close the circuit to sound analarm, and, as previously stated, the alarm will continue to ring untilthe occupant of the house manually opens the switch 25.

The deviceis extremely simple inconstruction and capable of beinginstalled at a minimum expense, and will produce maximum results withpractically no attention on the part of the occupant of the house orother building in which the system is installed.

Having thus described the invention, I claim:' 1. In a burglar alarm, acarrying bar, the bar being angular in cross section to provide opposedside faces and an outer face, a conductor strip extending longitudinallyupon one side 'face of the bar for the full length thereof, a conductorstrip extending longitudinally upon the outer face of the bar for thefull length thereof out of contact with the first strip and in insulatedrelation thereto, U-shaped loops of conductive material straddling saidbarwith the bridge portion of each loop extending across the outer faceof the bar'in spaced relation to the second strip, the arms of each loopbeing secured against the side faces of the bar with one'arm incontactingengagement with the strip,c.and spring-biased contacts formedfrom strands extending longitudinally of the bar through the loopstransversely thereof between the second strip'and bridge portions of theloops, each contact having one end anchored to the second strip and or"its own resiliency'urged toward a position for engaging one arm of thecompanion loop, the other end portion of each contactbeing adapted forengagement by a pull wire whereby the contacts may be held out of normalengagement with the last mentioned arms of the loops by tensioning thewires and move into engagement therewith of their own resiliency whenreleased, the contacts being also movable into engagement with theotherarms of the loops by abnormal pull upon the wires.

2. In a burglar alarm, a carrying bar, conductor strips extendinglongitudinally of said bar for the full length thereof and spacedtransversely from each other, loops extending transversely of said barwith'their intermediate portions extending across one strip in spacedrelation thereto and their end portions secured to the bar and insulatedfrom said strips, one end portion of each loop engaging the other strip,and spring-biased contacts extending longitudinally of said bar throughsaid loops in spaced relation to the loops, each contact having one endanchored to the first strip and biased toward a position for engagementwith its companion loop, the other end portion of each contact beingadapted for engagement with a pull wire whereby upon tensioning thewires the contacts maybe drawn to a set position out of engagement withthe loops, release of the pull wires perrm'tting return of the contactsinto engagement with the loops.

FRANCIS I-I. STOTTS. [L.s.]

